System of electric-motor control.



'No. 815,304. PATENTED MAR. 13, 1906.

(LA. MUDGE.

SYSTEM OF ELECTRIC MOTOR CONTROL. APPLICATION FILED JUNE 27. 1905.

O Q a N 2 SHEETS-SHEET 1' j awo'uwgw ua 3 0% RRR O WITNESSES.-

'PATENTED MAR. 13, 1906.

' 0. A. MUDGE.

SYSTEM OF ELECTRIC MOTOR CONTROL.

APPLICATION FILED JUNE 27. 1905.

2 SHEETSSHEET 2.

wmvE ssE8.- JWC nrromvsro preventing abnormal currentefiow through;

; the motors .at' any time and also for keeping 'onA- L-Esn. Moose,

citizen of the-United States, residingin New York, borough of Manhattan, county andor NEW roams.

I SYSTEM OF ELECTRIC-MOTOR CONTROL.

Specification of Letters Patent.

Patented March 13, 1906.

. n lidaion filed'March 2', 1905, Serial No.-248,121i Divided and this application filed June 27,1905. serial No. 267,204.

To all whom it may concern:

Be it known that I, CHARLES A. MUDGE, a

State of New York, have made anew and useful. Invention in Systems of Electric-Motor Control, of'which the following is a specification. v

My invention relates articularly to improvements in systems 0 control for the motors of electrically-propelled cars or vehicles, althou h it is applicablev enerally to the contro of electric motors wliere it is desired to operate the same at one or more relatively distant oints,'and the present application is directe to a'modified form of apparatus disclosedinFi ures15,16,17,18,'19,and20ofthe drawings 0 a prior patent granted to me on the end of the specification.

the 7th day of November, 1905, No. 804,156. .The objects of the present invention are substantially the same as those disclosed in the before-mentioned patent, the material points of novelty lying, essentially, in the I r structural device hereinafter .described, and

illustrated in the accompanying drawings, and particularly pointed out in the claims at For a full and clear understanding of my i invention, such as will enable others" skilled in the art to construct and use thesame, ref

. erence is had to the accompanying? drawings in which- 3 5 electrically-propelled car, the portable pri- Fig. 1 is a diagrammatic view of this medi fied form of my improved system of con-- trol, illustrating the same as applied to an mary or master controller being shown on' the left as attachedto' the dashboard thereof at one endof the car and .on the right to the circuit-controlling contacts developed ahd operativelyconnected to the controllingcircuits, the main operating device being shown inpart elevational, part sectional, view and operatively connected through rack-and-pin- .ion' gearing. and shafting to the main controller and motor-circui'tcombiner and cirwits and circuit connections, wherebythe system may be effectually operated through the agency of compressed air, gas, or a liquid, illustrating-also the application of means for I the currentflow practically constant therethrough during acceleration. Fig. 2 is an enlarged sectional view taken through the main operating device, illustrating its opera .tive connection through rackand.-pinion gearing with the primary driving-shaft and. means for effecting the operation of said de vice through the agency of-compressed air, gas, or a liquid, the controlling-valves being illustrated as electrically controlled. Fig. 3 is a detail sectional view taken through one of the coils and that partof the main controlling device which prevents abnormal currentflow through the motors at any time and also stant therethrough during acceleration. Fig.

troller of the drum or cylinder type, in which there is utilized a single controller-handle adapted to perform the functions usually attributable to the single controllere-handle and reversing-lever of ordinary types of motorcontrollers such as are used in electric-railway yste'ms. Fig; 5 is a vertical sectional as seen looking thereat from the bottom toward ,the top of the drawings in the direction of the arrows. Fig. 6- is a transverse sectional view taken through Fig. 5 on. the line Z Z and as seen looking thereat from the ward the bottom of the drawings. g

In my prior patent above referred to'l of which the present application is av division, reference is made to the advisability oflo'cat ing the operative or controlling parts of asystem of motors like that illustrated in the ac-. companying drawings at points relatively e'lfecting such control through the agency"v of currents of relatively small volume and a number of other desirable features azttrrbht system herein described and claimed is inthe main a modified form, are'poin'ted out. For the purpose of avoiding unnecessary prolixity in the present application reference therefore had to the above-11amed patentas to these matters.

several parts of the system for the purpose of etf'ecting the operation of the various appa- 4 is a plan view of the primary or master condistant from the motors themselves of" able to the system described and claimed in the above-named patent and' oftwhicligthe Referring now to the'drawings in" detaihit is to be; noted at the outset that allof the controlhng-conductors which connect the for keeping the current-flow practically coni view taken through Fig. 4 on-the line Y Y and top toratus are represented by'light'lines and by master controller, shown at the left of the figure as incased in the nietstllicboxand at thev right as having its cylinder developed, bein rovided with movable contacts'A, B, .an O, A being ahead and B backcontacts. sw is a multiple switch for disconnecting all of the conductors to to z, inclusive, from the circuit. sr is a secondary resistance for limiting the current-flow from-the main or working circuit W to the control-conductor w. MM isthe main operating device, (illustrated in detail in Figs. 2' and 3,) which shows plainly the parts operated by compressed air as well as'those operated by electrical energy. MC isthe main controller, and RH is a mam resistance divided into sections, as shown, and connected by the conductors W to W to stationary contact-fingersin the. main controller, and MR is the motor-circuit combiner. The movable contactstrips for cutting the resistance into and out of the cir cuit are carried 1) the drum of the main con-v .trolle'r MC, whic is supported by the shaft and the motor-circuit combiner MR by the shaft S frame of the main operating device MM.

and C are solenoid coils for operating the motor-circuit combiner MR and are included in the control-circuits y and-u. A A F F represent the armatures and field-coils of two electric motorsof the series type connected to the contact-fingers of the motor-circuit combiner MR. The main controller-MC is represented'as'being of the drum .or cylinder -t e, theconstruction and operation of which is amiliar to those intheart and is shown as opening the motor-circuit in" passing from series toparallel combination of the motors.

v I do not limit [myself to thisparticular construction, as it is evident that any other const'ruction which could be operativel connccted to the shaft S might be use in its stead, The motor circuit combiner MR, which is'carried by the shaft 8*, is the same as that described in my before-mentioned prior patent, and-reference may bemade to" the text and drawings thereof for a detail description of its construction and operation.

Referring to Fig. 2, I will describe the main operating device MM. The-piston P is. located. in an air-cylinder and is provided with a rack R and a-return-spring, said rack 1 biased.

both shafts being connected to the shaft S, which is journaled in the supportin I 'controlisof the t beipg geared to the pinion P and main shaft S, P? is anin let-pipe running to a sup l of compressed air or gas, (not shown,) and V are respectively the main and exhaust valves.

C and C are solenoids for controlling the movement of the valves V and the arrangement being such that when alr'ls admitted through the valve V it moves the piston P from right to left a ainst the action of the spring, and when ex austed throu h valve V the piston moves from left to rig t under the returnaction of the sprin In Fig. 3 is hown the mean app icable to this form of the invention for preventing abnormal currentflow through the motorsat any time and also forkeeping the current fiow practically constant therethrough during acceleration. In this part ofthe apparatus the- I coils C" and C are sol-elated that as the current in the coil U'increases it (produces a field .tendwiringof each car the conductors w to w, inclusive, are preferably inclosed in a flexible conduit-or cable, like 0'', and at each end of the car these conductorsare provided with con-.

tacts, as shown diagrammatically at the right of 1 fox-the purpose of effecting the I 7 915 Q electricalconnections of one or morecars, so

as to make the system of controlapplicable to train service, a flexible interconnecting cable between each pair of cars being provided with contacts for connecting the ad- Loining sets of contacts above referred to, it

eing understood that when a number of cars are thus: connected together the system of known as-the mult leunit "system... rrepresents the'.trol ey- =conductor orthird'-rail',- and-T the currentcollector or trolley-s ow to F' .4, 5, and 6, and first 'fi the especial form of Referri n to Fig. 6, l will descn primary or master controllerj applicable for use inconnecti'on with this novel modified system of'my invention. CB represent'sthe primary or master, controller inclosed ina metallic box, as shown, the same being illustrated in Fi I as attached directly 'tolthe dashboard on one of the platforms of a car through the agency of alocking-plate 1 I, having a slot 10, the arra ement bein such that the controller can on y be remove when the locking-pin 9 and lever 7 are in the posi-' tion shown in Fig. 6, all'substantially as described and shownin thebefore-mentioned nently in positionat allltimes wlien the controller-handle'is in ary' otherposition, than what is known as o prior atent andin which patent claims are bodied with relation to this particular feature of lockingfthe master-controller-pcrma position. 1 m represents an electromagnet-which is-provided with tweenergrzmg-coilsfone in circuit with. the stationary contact-a and the controllingconductors ui ac yjandthe other with the stationary contactf b and controlling-conductors w 90 3 running, respectively, .to. the revrsing-solenoidsC C thearmature of. the

electromagnet being placed directly. above ,the yielding supported contact'c insuGhmanner as tohold said contact away from the or B contacts, according as the handle H s rotated either-to the left or to right when the larly described in connection withthe descrip-' magnet m is energized, as will be more particution of the mode of operation.

The several indicated positions for ahead I and back are directly on the top plate of the I i 4 34 in either direction from the numeral 0 in-' controller and indicated by the numerals 1 f2 dicatingthe off position, and the other nu,-

merals the ahead or back positions, according as the handle is turned, as shown by the curved arrows. (See Fig. 4.) Referrlng now to the diagrammatlc view illustrated in Fig. 1 Iwill describe the mode of operation upon the suppos'tion that the .port

able primary or, master controller CB has been'transferred from the position shown at the left of the drawing to the right-hand po sition, where the op crating-contacts are shown,

as developed. With the contacts in the posi-;

.tion shown in this development there is elec tacts A and BC are moved under the contactlenoid-coil C to the stationary brush p on,

fingers to position marked 1, which cornpletes the circuit from if too, through the mag,- net m, to conductor w 00 y, through so-',-'

the drum of the motor-circuit combiner MR, where the circuit is interrupted, which means; thatthemotors are properly connected for, a forward motion of the car as observed; from the right-hand platform. If areverse motion of the car is desired, thecontacts Bf of the master-controller are moved underthe .sponding to that'in the .forward position, ,which completes the .ircuit from t'to '65 through the magnet m, raising. the finger c from its contact-strip, to conductor w x 1/ 1 contact-fingers to a-pos ition l-corre-',

through. solenoid-coil C to the stationary, brush 1:), contact-strip s, conductor y, coil of the magncticclutch M, to e artliatlil'.

4 Current flows through this circuit and energizesthe solenoid G which attracts its core, The magnetic clutchM is attracted and held fast to'the' disk D, which is attached 'toth; shaft S and \the motorecircuit combiner MB; is rotated until-[the current is interrupted by the contact stri s"'passing from under the lower right-han brush p, as :it slides off} the circuit-connecting contact-fingers carried by thc'motor-circuit combiner MR are in the position S, giving roper connections T61 a reverse motion of the car as observed from ,theright 'hand platform. As soon as-the motor-circuit combiner is in its proper-position the circuit is interrupted and themag- 'net m in the master-controller is denergized,

allowing the contact-finger c to fall on its contact-strip, which completes the circuit (1 w m yf, coil 0 to earth at E, closing the exhaust-valve V. I

Position 2 of ,the master oontr'oller establishes the circuit e w r y t Z Z t 1 coil G5, to earthrat E. This opens the valve V, admitting compressed air or gas through the inlet-pipe P to the rear of the piston P, driving 'it forward, and, thus rotating the main controller MC until the contact at t Z is broken, which interrupts the current through the coil C and the valve V drops, fcutting off any further air-supply, and the main controller MO is held in position 1., which is the first running position of the motorsseries combination with all resistance in circuit. Position 3 of the master-controller advances the main controller in a similar manner to position 5motors in series combination-with all resistance out of circuit 1 Position 1 of the mastercontroller advances the main controller to position 9 motors in parallel combination with all re sistance out of circuit. Between positions 5 and 6 of the main controller the motor-circuit combineroperates to throw the motors into parallel. This is effected by the cam D, Fig. 1, moving the roll T", which is attached tothe crank-arm K through the link L away from the center ofthe shaft S, thus turning the crank-arm K and the attached cient to move the .contact-stripsfarenough so that the contact-terminals of thamotoi circuit combiner shall take the position P or 1?, giving parallel combinatio ns tors for forward or reverse'rurinmg. Inasmuch as this operation takes place while the I ,motor-current 1s mterrupte'd,'no arcing can possibly occur'at the motor circ uit-combiner terminals, and hence no arc-interrupting d6", vice is required.

If it is desired to run at a speed corresponding to. any ,other than positions 1, 5, or 59 of the main controller; the mastercontroller is returned to position 1 when the desired speed has been reached. This arrests any further movement-of the main operating device and the main'controller. To cut the -motors out of circuit, the master-controller is returned to off or 0 position, which in-' terrupts allcontrol-circuits and the valve V of the main operating'device opens, allowing thecontact-strip s, which takes place when. theair the cylinder to exhaust, and the f the mo- Y from series to paralle 4S rupted, and consequently there is noop os-.

'ing fieldto that formed the coil C piston P isreturned by'the s position, as illustratedin Fig, 2. I Fig. 3 represents the means'employed for obtaining a constant acceleration of the motors as well as for keeping the motor-current within a predetermined hmit. connecte in either series or shunt with one of the motors, the same being represented in Fig. 1 in series, and the magnetic field produced by it varies with the r'notor'current1 I The valve V .isadjusted to open wide enough /which would t .5

torque s'uflicientfor the the current incoil 20 through the'influence of the coil to give I ential action a field duced by coil, C? and-the valve'Weloses, therebyretardingthe movement of the piselectromotive force of theunotors increases the current in the coil O isdecreased, allow- I I, ing the valve V to open ag'aimand the piston I determined value. I

" it possible'to turn the master-controller im- 'mediately to' the full parall termined acceleration independent oft ewill of the'motorman. I I I In case the' motor-cu I any time during the foperation of main open widely, 'a'llowin to move more rapidly. In this manner the current in the motor-circuit is kept ra'cticallyv constant during the starting 0 the motors and is alsoke t from exceeding a prehis feature also makes ru sp s tion, the car starting forward at a redeent'is'interruptedat operating (IGVIOGH forins'tance, in passing made very rapidly. I that the current in the coil 0, Fig. 3,1is interw 'ch actsto open the valve V to its fullest extent, thereby allowing more air to rush in behind the piston'P, thus driving it rapidly forward,

I the main controller being turned-quickly to a opensthe circuit between the series and lpara 1 heyi' had. his autdmatic ssparallel position, having the same current value er motor that the last series position feature insures the shortest interruption of current, and hence motor torque, in that form of controller which el combinations of motorsi If the tro current is interru ted at anytime, all of the apparatus contro ing the motor-currents returns immediately to the off osition' without any action on;the part of t e motorman, and if he does not return the master-con- .trol-ler to the off position before the trolleycurrent' is again eats tb lished the motor-con- The coil C ove' an amount which produces a desired acceleration, 0 produces by itsjdifler j which weakens; that pro- I I of the drawings, I ton IP and. the cutting out of the ma'inr'esist- I ance in the, motor-circuit.

- I As the countermotion of an airing of-contacts t pneumatic devices.

with the form of main controller shown in Fig. l-thejvalve Yfwould .th

this transition his isdue to-the fact troller is operate toits oflIl trolling ap'paratuslis automatically turned into that pos tion corresponding to the s of the car at the time the trolleyscurrent was reestablished. I 1 I I I do notlimit my invention .to the numerous details of construction illustrated in the accom an in drawings and hereinbefore de- A y g scribe as a number of the features thereof might be materially departed from and still ter made. I

I also desire it understood that while I come within the scope of my claims hereinafhave shown my meansof motor control as applicable to two motors of theseries type I do notwish to be limited specifically to this combination, as the'same' might be ap lied to any number of motors, either of the meet or alternating current type.

'Itis of course obvious-that numerous, de-' tails in the nature of hand-switches, fuses, circuit-breakers, &c., are purposely left out so as to avoid confusion.

. I am aware that there are many systems of motor control in which the current-controlling devices are operated pneumatically; but to-my knowledge 'there' are none in which thesedeviees are operated by the continued application =of-a fluid medium. Most of the systems heretofore ed operate either by ste by-step motion of the controller produced li} the reciprocating lston or the successive clos- I n t e system herein described the pneumatically-operated device advances far enough in one direction to turn proposed and constructon h separately-operated IOO theficontrollerfthrough the different running positions of themotors either in a step bystop motion or a continuous motion, dependmg .upon the wa in which the master-conand also upon the value of "stance, if the current is turned on turned "rapidly forward, a vancing the controller'to a position corres nding to .t lie speed, after which it pr sin a step-bystep motion untilthe'motorsare'in the posie current in the motor-circuit. For in- I while the car is coasting the main oyerating device istion indicated by the handleof the mastercontroller.-- The manner inwhich thisIim port-ant feature is attain is new, as faras I am aware,'and the claims appended hereto are intended to include it.

' Having thus described my invention, what I claim, and desire to secure by- Letters Patent of the United States, is-

1. In a system of motor control fluid meansoperatively connected. with current-controlling devices; in combination with independent inlet and exhaust valves therefor and independent electromagnetic meansfor operating said valves, whereby. said-fluid means is operated through successive steps by the continued-application of a fluid .r nedlum, substantially as described.

ling devices; in combination with independent inlet and exhaust valves therefor and independent electromagnetic means for operating' said valves; together witha master-controller provided with indicating means, the fluid means being advanced by the continued application'of a fluid medium, substantially as described. I 3. In a system of motor control fluid means operatively connected with current-controlling devices, said. fluid means embracing a piston, a cylinder and independentelectrid ally-controlled valves therefor, the arrangement being such that they piston is advanced by the continued application of a fluid medium, substantially as described. 4. Ina system of motor control pneumatic means 0 eratively connected to current-controlling evices, said means embracing a piston, and independent] -operated valves for advancing the piston t rough the continued application of a fluid medium; in combination with a master-controller provided with indicating means, substantially as described, 5. In a system of motor control pneumatic means operatively' connected with currentcontrolling devices; in combination with elec- M tromagnetic control-valves therefor, and oir cuit connectionswhereby the speed at which the pneumatic means operates is made dependent upon the motor-current, and the movement of the operative parts of .the pneumatic means is made continuous by the application of av fluid medium, substantially as de- .scribed. v 6. Ina system of motor control pneumatic means operatively connected with currentcontrolling devices; in combinationwith electrically-operated valves independently controlled for stoppin and retaining said controllingdevices 1n ifferent positions, the operative parts of the pneumatic means'being advanced by the continued application of a pneumatic .medium, substantially as described. i v 7 In a system of motor control a mastercontroller, a -main neumatio operating device and electrica I connections therefor,

whereby the operatin device is continuously advanced'througli successive steps by the ap lication of a pneumatic mediunrmade depen ent upon the motor-current; in combination with current-controlling devices operatively connected to the main operating device, andmeans at the niaster controller for indicating the different steps, substantially as described. g 8, In a system of motor control aimain operating device, current controlling means T mechanically connected thereto, a" master controller electrically connected thereto, and circuits and circuit connections between the motorsand the main operating device,wheretrol embracing two circuits one of whichis .valve, whereby the motor-current is kept as described.

by the movable partsof said main operating device are advanced at a rate made dependent upon the motor-current through success1ve steps by the continued application of a pneumatic medium, said master-controller being provided with means for indicating any definite step, substantially as described.

9. In asystemof motor control acontroller; a pneumatic main operating device therefor provided with electromagnetic means of con- 7 5 included in the motor-circuit-proper and embraces an electromagnetically controlled practically constant at starting, substantially 8o 10. In a system-of motor control a controller; a niain'operating device provided with pneumatic ,means for advancing it through successive steps; in combination with additional means embracing two electric circuits so related that the'effects produced by one of said circuits tend to neutralize those of the other circuit, thereby maintaining the current-neutralizing circuit within-a predetermined value, substantially as described.

11. 'In asystem of motor control a main operating device pneumatically operated and. current-controlling devices connected there to, the said main operating device embracing an electrically-controlled valve which operates insuch a manner that the current-co'n-l trolling devices tend to keep the motor-current constant during the starting of the motors as well as to prevent said current from exceed- [0Q valve being operated by the combined influence of the motor-current, or a part thereof, and .an independent current thereto, substanr05 tially as described.

12. In a system of motor control a controller; pneumatic operating means therefor; in combination with two independent control ling-circuits including an electromagnetic- I re ally-controlled valve adapted to operate in such manner that the motor-current is maintained practically constant during starting, substantially as described. v

13. In a system of motor control a control- 1 r 5 ler; pneumatic o crating means therefor; in combination wit twoindependent controllingecircuits therefor, one of which is in- -=luded in the motor-circuit and both of which include an electromagnetic controlling-valve, the arrangement being such that the com bined current effects of said circuits main tain the 1notor-currentwithin a fixed value during the operation of the motors, substantially as described.

14; In a system of motor controla control- Y ler and pneumatic o crating means therefor; in combination wit valves and controlling-- electromagnets therefor; together with circuits and circuit connections whereby the 1 0 normalspeed ofthe meansfis automaticallyincreas'ed or decreased by the operration of the said, arts when the, motor-curstantially as described. 15.- In a system ofmotor control a main ac-conductors whereby the control-circuits of 1 one car may be connected to the correspondfling-circuits of another car; a ortable master- .controller adapted to be uti lzed on any car;

i in combination withele'ctric motors and current-controlling devices .on one or more cars, said devices being operated by a single neumatic operating devicellocated on eac car and advanced through successive steps at a speed depending upon the motor-current by t e continued application of a pneumatic medium and electrically controlled by'the'" substantially as described. v .t

, I 17; In a system of motor control-for elec- .35 trio-railway cars coupled together to form a train, control-circuits on each caifi d interconnecting contacts and conductors whereby the control-circuits on one car may be connectcd withthose of the adjoining car;

4o combination with electric motors on one or more cars, a single pneumatic operating device o erated on each [car and advanced throug successiye steps at a speed'depending upon the motor-currentby the continued application of a pneumaticmedium, said operatin device being corinectedtocurrentcontro ling devices together with a ortable master-controller from any of the said cars,

' master-controlleradapted to house on any car in the'train, .saidmaster-controller; being -'so connected to thecurrentfcontrolling devices and the pneumatically-operating de-' a vice through the control-circuits that it controls and indicates at all times the combinatio'iis of" the motors, substantially as described. I

' 18. A master-controller embracing means whereby the forward or reverse connections and the running combinations of the motors it controls are madethrough the operation of a single handle; in combination with electro' magnetic means embracing a part of the master-controller and operating so that they motorsreceive' current only after the said forward or reverse connections have been made, substanti'allyasdescr1bed.. V

circuit com motors, substantiall 20. In a system 0 motor controls. masterarts motors to receive current be erases 7 19. Inc mm: motorcontrola motormer, a main controller, and a portable master controller embracingh electromagn'etic means for so'governing e o eration of the motor-circuit combiner and t e 79 main controller that the latter cannot be operated until the former is in a position giving either forward or reverse connections of the asdescribed.

controller embracing a magnet "adapted to attract a contact-finger away from its contact-strip and to thus interrupt a circuit controllin the operation of a controller,

said circuit remaining interrupted until a" 80 motor-circuit combiner has operated to give the forward or reverse connections 'of the motors, thereby making it impossible for the ore they have been properly connected, substantially as de-' 8 5 scribed. 5 5

21 A portable master-controller embracing a single. contact-cylinder operated by a single-handle through which the forward, re-

verse and running combinations of the motor 0 or motors it controls are made, said controller being so arrangedlthat itlcannot be removed from its seat without first interruptin l circuit connections through it, substontla y ESLiQSCIjibGd. a

' "'22. A portable master-controller embracing. eleatromagnetic means, circuits and cir cult c 'ections such that it isimpos'sible for the motors controlled to receive current before they are interconnected fora forward or 1 00 re erse rotation, and means at the mastercontroller for indicatingithe same. 23. In a system of motor control for. electric-railway cars a portable master-controller adaptedto be connected at-difierent points in a control-circuit extending throu bout the cars, one .or moreof. which is supp ied with electric motors and suitable controlling apparatus; said apparatus bein operated b a single l'luid-operati device ocated on eac 1 1o motor-car and contro led by electric means through the master-controller, substantially as described. I

24. In a system of motor control acontroller connected with pneumatic means for operating it; in combination with regulating means and circuits and circuit connections whereby said neumatic means operates more rapidly w en the motor-current falls below a predetermined value and operates slower, or sto sentirely, when the motorcurr'ent'excee s this va ue, substantially as described; 5

I 25-.' Two ormore electric motors and a main resistance therefor; inconbination with I 2 5 electrically-controlled pneumatic means for effecting 'various relations between the motors and the resistance; together with means for interruptin the motor'- circuit, said pneumatic means being so constructed that its 3 scribed 27. In a system of motor control, a main movable part will advance at increased speed during the intervals that the motor-circuit is interru ted, substantially as described.

26. n a system of motor control pneu' matic means for 0 erating the motor-cornv trolling apparatus; in combination with electromagnetic means for so controlling the o eration of 'saidpneumatic means that t e speed of operation is inversely proportiogal to the motor-current, substantially as a econtroller a pneumatico erating device conv nected thereto and provi ed With an exhaust- 4 valve adapted to be operated by a single conth'arrangement being such that if the cur,

rent-flow through said magnet be interrupted at any time during the operation of the motors the controlling apparatus willbe automatically turned to its off or open-circuit position by said neumatic device, substantially as described In testimony whereof I have signed my I name to this specification in the presence of two subscribing witnesses.

CHARLES A. MUDGE.

Witnesses:

C. J. KINTNER, M. F. KEATING. 

